This project aims to: (1) determine the relationship between performance on a standardized max treadmill test and performance on the 400m component of the LDCW, including variation by fitness level; (2) obtain an estimate of VO2max from time to complete 400m, among other parameters (e.g., ending HR, weight, sex, age); (3) determine the need to increase test ceiling; (4) obtain additional data on the relationship between 20m walking speed, 2-min distance, and 400m time; (5) determine reproducibility over a short time period; and (6) evaluate the advantages of the LDCW over treadmill-based tests for measuring exercise tolerance in older adults. Subjects will consist of 30 men and 30 women, 60 years or older (10 men and 10 women from each age- and sex-specific tertile of VO2max and will be recruited from participants in the BLSA who have completed a max treadmill test. Subjects will be administered the Health ABC LDCW as part of their regular visit for the BLSA, the day after they undergo treadmill testing. About half of the subjects will be administered the Health ABC LDCW a second time, the morning of their third examination day.The primary outcomes are to provide: (1) a validated alternative to max treadmill-based tests of exercise tolerance that is safe and acceptable for use in longitudinal population-based studies of older adults and (2) equations for estimating VO2max from time to walk 400m applicable to older adults. We anticipate that validation of a low cost and safe alternative to treadmill testing will promote more widespread inclusion of exercise tolerance testing in studies of older adults and thereby facilitate increased understanding of the disabling process. In addition, the LDCW has the potential for use in clinical settings as an indicator of preclinical functional decline and for screening to identify those most in need of early intervention.The protocol received IRB approval in April 1999 and testing was initiated in August 1999. - exercise tolerance, long distance corridor walk, - Human Subjects